#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

int main(int argc,char **argv){
    int (*convcase[2])(int) = {toupper,tolower};
    int func;
    int result = EXIT_SUCCESS;

    int ch;

    if(argc > 0){
        if(toupper((unsigned char)argv[0][0]) == 'U')
            func = 0;
        else
            func = 1;
        while((ch=getchar())!=EOF){
            ch = (*convcase[func])((unsigned char)ch);
            putchar(ch);
        }
    }
    else {
        fprintf(stderr, "Unknown name. Can't decide what to do.\n");
        result=EXIT_FAILURE;
    }

    return result;
}
